few days back i was facing the same kind of problem
you see three wires are coming out of the brush less motor
1. one red one is for +ve
2. black one is for - ve
3 third yellow is for the speed of motor ie throttle
color coding may very but the method is same.
now first two can change the direction of the motor by changing the first two wire
problem arrives when the third wire is not placed at the proper spot in the esc
i think you have to position the third wire correctly may be problem will solve out.
other thing you might help is
check our transmitter throttle settings
read the calibration process of your esc again maybe some step is missing.